SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5809584dc6d67fb336c527af9368e7aa64f4602dc378f186e33f8cd2319d0942' 
  AND token = '9XiSQRPjK1mATKFLjQT9VpiXpKX4qVM/1kvZCqbKThQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}